Newborns who weigh less than 5.8 pounds (2631 grams) are diagnosed as low birth weight. Low birth weight is a concern because it can cause complications in the newborn, such as difficulty feeding and gaining weight, breathing problems, and even sudden infant death syndrome (SIDS). Low birth weight may be the result of a premature birth or intrauterine growth restriction, but other factors, including the mother's health, can also increase a newborn's risk.
Researchers from Singapore wanted to examine the relationship between maternal caffeine intake during pregnancy and the risk of low birth weight (less than 5.5 pounds/2500 grams). The study, published in BMC Medicine, found that higher maternal caffeine intake during pregnancy was associated with a higher risk of delivering low birth weight infants.
The systematic review included 13 prospective observational studies evaluating the effect of maternal caffeine use during pregnancy on the risk of low birth weight. There were a total of 100,762 participants in the studies. Women who had newborns with intrauterine growth restriction and small for gestational age age were included in the low birth weight outcomes.
When the study compared pregnant women who did not consume caffeine or consumed very low caffeine, researchers found that women who did consume caffeine had a:
A systematic review is considered a reliable form of research because it combines several smaller studies. The higher the number of participants the more reliable the results may be. However, the systematic review is only as reliable as the studies that were included. In this case, the included trials were observational trials which means the results can not establish cause and effect but only show possible links. In addition, women who had newborns with intrauterine growth restriction and small for gestational age were included in the outcomes. Since these infants' would have low birth weight because of previous conditions, their inclusion in the outcome makes the results less reliable.
Caffeine can pass through the placenta and reach the fetus in pregnant woman but the exact effects on the fetus and safe amounts of caffeine are not very clear. The American College of Obstetricians and Gynecologists currently recommends that pregnant women consume less than 200 mg/day of caffeine (about 1-2 cups of coffee). If you are pregnant, or thinking about becoming pregnant, you may want to limit your caffeine intake. Here are some tips:
If you are pregnant, talk to your health care team about your diet and any dietary changes you should consider.
The American Congress of Obstetricians and Gynecologists
March of Dimes
American College of Obstetricians and Gynecologists. ACOG Committee Opinion No. 462: Moderate caffeine consumption during pregnancy. Obstet Gynecol. 2010 Aug;116(2 Pt 1):476-468. Available at: http://www.acog.org/Resources-And-Publications/Committee-Opinions/Committee-on-Obstetric-Practice/Moderate-Caffeine-Consumption-During-Pregnancy. Accessed October 16, 2014.
Caffeine in pregnancy. March of Dimes website. Available at: http://www.marchofdimes.org/pregnancy/caffeine-in-pregnancy.aspx. Updated June 2012. Accessed October 16, 2014.
Chen L, Wu Y, et al. Maternal caffeine intake during pregnancy is associated with risk of low birth weight: a systematic review and dose-response meta-analysis. BMC Medicine. 2014.12:174.
Last reviewed October 2014 by Michael Woods, MD